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Accurate emulation of tilemap advancement timings

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This commit is contained in:
Lior Halphon 2020-03-03 02:21:19 +02:00
parent e846f4f3b0
commit 409ab2a6d4
3 changed files with 24 additions and 16 deletions
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32
Core/display.c
View File

@ -547,7 +547,7 @@ static void advance_fetcher_state_machine(GB_gameboy_t *gb)
GB_FETCHER_SLEEP,
} fetcher_step_t;
fetcher_step_t fetcher_state_machine [8] = {
fetcher_step_t fetcher_state_machine [9] = {
GB_FETCHER_SLEEP,
GB_FETCHER_GET_TILE,
GB_FETCHER_SLEEP,
@ -555,9 +555,13 @@ static void advance_fetcher_state_machine(GB_gameboy_t *gb)
GB_FETCHER_SLEEP,
GB_FETCHER_GET_TILE_DATA_HIGH,
GB_FETCHER_PUSH,
GB_FETCHER_PUSH, // Compatibility
GB_FETCHER_PUSH,
GB_FETCHER_PUSH,
};
if (gb->fetcher_state >= sizeof(fetcher_state_machine)) {
gb->fetcher_state = 0;
}
switch (fetcher_state_machine[gb->fetcher_state]) {
case GB_FETCHER_GET_TILE: {
uint16_t map = 0x1800;
@ -659,19 +663,23 @@ static void advance_fetcher_state_machine(GB_gameboy_t *gb)
}
}
gb->fetcher_state++;
if (gb->wx_triggered) {
gb->window_tile_x++;
gb->window_tile_x &= 0x1f;
}
// fallthrough
case GB_FETCHER_PUSH: {
if (fifo_size(&gb->bg_fifo) > 0) break;
if (gb->wx_triggered) {
gb->window_tile_x++;
gb->window_tile_x &= 0x1f;
}
else {
if (gb->fetcher_state == 7) {
/* The background map index increase at this specific point. If this state is not reached,
it will simply not increase. */
gb->fetcher_x++;
gb->fetcher_x &= 0x1f;
}
if (gb->fetcher_state < 8) {
gb->fetcher_state++;
}
if (fifo_size(&gb->bg_fifo) > 0) break;
fifo_push_bg_row(&gb->bg_fifo, gb->current_tile_data[0], gb->current_tile_data[1],
gb->current_tile_attributes & 7, gb->current_tile_attributes & 0x80, gb->current_tile_attributes & 0x20);
@ -685,8 +693,6 @@ static void advance_fetcher_state_machine(GB_gameboy_t *gb)
}
break;
}
gb->fetcher_state &= 7;
}
static uint16_t get_object_line_address(GB_gameboy_t *gb, const GB_object_t *object)
@ -946,7 +952,7 @@ void GB_display_run(GB_gameboy_t *gb, uint8_t cycles)
gb->fetcher_state = 0;
while (true) {
/* Handle window */
/* TODO: It appears that WX checks if the window beings *next* pixel, not *this* pixel. For this reason,
/* TODO: It appears that WX checks if the window begins *next* pixel, not *this* pixel. For this reason,
WX=167 has no effect at all (It checks if the PPU X position is 161, which never happens) and WX=166
has weird artifacts (It appears to activate the window during HBlank, as PPU X is temporarily 160 at
that point. The code should be updated to represent this, and this will fix the time travel hack in

4
Core/memory.c
View File

@ -742,6 +742,10 @@ static void write_high_memory(GB_gameboy_t *gb, uint16_t addr, uint8_t value)
GB_lcd_off(gb);
}
gb->io_registers[GB_IO_LCDC] = value;
if (!(value & 0x20)) {
gb->wx_triggered = false;
gb->wx166_glitch = false;
}
return;
case GB_IO_STAT:

2
Core/save_state.c
View File

@ -267,7 +267,6 @@ int GB_load_state(GB_gameboy_t *gb, const char *path)
gb->oam_fifo.write_end &= 0xF;
gb->object_low_line_address &= gb->vram_size & ~1;
gb->fetcher_x &= 0x1f;
gb->fetcher_state &= 7;
if (gb->object_priority == GB_OBJECT_PRIORITY_UNDEFINED) {
gb->object_priority = gb->cgb_mode? GB_OBJECT_PRIORITY_INDEX : GB_OBJECT_PRIORITY_X;
@ -379,7 +378,6 @@ int GB_load_state_from_buffer(GB_gameboy_t *gb, const uint8_t *buffer, size_t le
gb->oam_fifo.write_end &= 0xF;
gb->object_low_line_address &= gb->vram_size & ~1;
gb->fetcher_x &= 0x1f;
gb->fetcher_state &= 7;
if (gb->object_priority == GB_OBJECT_PRIORITY_UNDEFINED) {
gb->object_priority = gb->cgb_mode? GB_OBJECT_PRIORITY_INDEX : GB_OBJECT_PRIORITY_X;